Turbomachine component damping structure and method of damping vibration of a turbomachine component

ABSTRACT

A turbomachine component includes a main body having a surface, and a damping structure mounted to the surface of the main body. The damping structure is formed from a material having a temperature dependent damping characteristic.

BACKGROUND OF THE INVENTION

Exemplary embodiments of the present invention relate to the art ofturbomachines and, more particularly, to a damping structure for aturbomachine component.

Turbomachines include a multitude of components, many of which rotate athigh speed during operation. The operation of the turbomachine subjectsmany of the turbomachine components to stresses resulting fromvibration. This includes compressor components, hot gas path (HGP)components, combustor sections and turbine components. Stressesresulting from vibration cause fatigue that shortens operational life ofturbomachine components.

BRIEF DESCRIPTION

In accordance with an exemplary embodiment of the invention, aturbomachine component includes a main body having a surface, and adamping structure mounted to the surface of the main body. The dampingstructure is formed from a material having a temperature dependentdamping characteristic.

In accordance with another exemplary embodiment of the invention, amethod of damping vibration of a turbomachine component includingmounting a damping structure to a surface of the turbomachine component.The damping structure is formed from a material having a temperaturedependent damping characteristic.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an example of a turbine bucket including a damping structurein accordance with an exemplary embodiment of the invention.

DETAILED DESCRIPTION

Referring to FIG. 1, a turbine component, shown in the form of a turbinebucket, constructed in accordance with exemplary embodiments of theinvention is indicated generally at 2. Turbine bucket 2 is formed from ahigh temperature alloy such as, but not limited to, alloys of nickel andincludes an airfoil or blade portion 4 and a base portion 6. Bladeportion 4 includes a main body 10 having a first end section 12 thatextends to a second end section 14 through an intermediate or airfoilsection 16. Airfoil section 16 includes a suction side surface 18 and apressure side surface 20. Base portion 6 includes a main body member 30having a first end portion 32 that extends to a second end portion 34through an intermediate portion 36. Intermediate section 36 includes afirst angel wing 40 that defines a first trench cavity 42 and a second,opposing angel wing 44 that defines a second trench cavity 46. Turbinebucket 2 is configured to be mounted to a rotor disk (not shown)adjacent a plurality of additional turbine buckets to form a turbinesection.

In accordance with the exemplary embodiment shown, turbine bucket 2includes a damping structure 60 secured to pressure side surface 20 ofairfoil section 16. As will become more fully evident below, dampingstructure 60 provides vibration damping characteristics when applied toairfoil section 16. In accordance with the exemplary embodiment, dampingstructure 60 is formed from a material having temperature dependentvibration damping characteristics. More specifically, damping structure60 includes a first damping characteristic at a first temperature and asecond damping characteristic at a second temperature. The first dampingcharacteristic changes to the second damping characteristic at a dampingtransition temperature. In this manner, turbine bucket 2 is providedwith a first level of damping during start up and, as operatingtemperatures and speeds increase, damping structure 60 passes throughthe transition temperature to provide an increased level of vibrationdamping.

In accordance with one aspect of the exemplary embodiment, dampingstructure 60 is formed from a stainless steel alloy having a dampingtransition temperature at about 900° F. (482.2° C.). Damping structure60 is secured to a surface of, for example airfoil section 16. Theamount of damping provided by damping structure 60 is dependent upon thetemperature at which a vibratory response occurs. That said, below about900° F. (482.2° C.) the damping is at a first level and above about 900°F. (482.2° C.), damping is at a second, higher level. The abovedescribed system provides a 2-14 times increase in damping to turbinebucket 2. Of course it should be realized that the above described rangeis but an exemplary embodiment of the invention. Other materials havingsimilar or different damping characteristics could also be employed. Theparticular materials employed depend upon desired dampingcharacteristics at particular operating parameters/temperatures of theturbomachine.

At this point it should be understood that while damping structure 60 isdescribed as being formed from stainless steel, other alloys, includingglass alloys, that have a damping transition temperature in a range ofabout 800° F.-1400° F. (426.6° C.-760° C.) can also be employed. Itshould also be understood that the particular mounting location ofdamping structure 60 can also vary. That is, instead of covering anentire airfoil section, damping structure 60 can be selectively appliedin high strain areas for maximum stress reduction. In addition, athermal barrier coating 70 can be applied over an interface betweendamping structure 60 and airfoil section 16 to provide protection fromspallation and oxidation.

Damping structure 60 can be applied to the desired turbomachinecomponent by a number of appropriate joining techniques depending on thematerials to be joined. For example, damping structure 60 can be appliedto airfoil section 16 using welding, brazing or plasma spray techniques.More over, damping structure 60 can be applied in a single layer,multiple layers or combined with a damping structure having dampingproperties tied to structural characteristics of the damping materialsuch as taught by co-pending U.S. patent application Ser. No.11/844,462, entitled “Structures for Damping of Turbine Components”filed on Aug. 24, 2007 incorporated herein by reference in the entirety.

In general, this written description uses examples to disclose theinvention, including the best mode, and also to enable any personskilled in the art to practice the invention, including making and usingany devices or systems and performing any incorporated methods. Thepatentable scope of the invention is defined by the claims, and mayinclude other examples that occur to those skilled in the art. Suchother examples are intended to be within the scope of exemplaryembodiments of the present invention if they have structural elementsthat do not differ from the literal language of the claims, or if theyinclude equivalent structural elements with insubstantial differencesfrom the literal language of the claims.

1. A turbomachine component comprising: a main body having a surface;and a damping structure mounted to the surface of the main body, thedamping structure formed from a material having a temperature dependentdamping characteristic.
 2. The turbomachine component according to claim1, wherein the damping structure includes a first damping characteristicat a first temperature and a second damping characteristic at a secondtemperature, the second temperature being distinct from the firsttemperature.
 3. The turbomachine component according to claim 2, whereinthe damping structure includes a damping transition temperature, thedamping transition temperature being between the first and secondtemperatures.
 4. The turbomachine component according to claim 3,wherein the damping transition temperature is in a range between about800° F. (426.6° C.) to about 1400° F. (760° C.).
 5. The turbomachinecomponent according to claim 4, wherein the damping transitiontemperature is about 900° F. (482.2° C.).
 6. The turbomachine componentaccording to claim 1, wherein the damping structure comprises stainlesssteel.
 7. The turbomachine component according to claim 1, wherein theturbomachine component includes at least one turbine bucket, the dampingstructure being mounted to a surface of the at least one turbine bucket.8. The turbomachine component according to claim 1, wherein the dampingstructure is mounted to a portion of the surface of the at least oneturbine bucket.
 9. The turbomachine component according to claim 1,wherein the damping structure is mounted to the surface of theturbomachine component by one of welding, brazing and plasma spraying.10. A method of damping vibration of a turbomachine component, themethod comprising: mounting a damping structure to a surface of theturbomachine component, the damping structure formed from a materialhaving a temperature dependent damping characteristic.
 11. The method ofclaim 10, wherein the damping structure is mounted to the surface of theturbomachine component by one of welding, brazing and plasma spraying.12. The method of claim 10, further comprising: damping vibration at afirst level when the turbomachine component is at a first temperature,and damping vibration at a second level when the turbomachine componentis at a second temperature, the second temperature being distinct fromthe first temperature.
 13. The method of claim 12, wherein damping thevibration at the first level occurs when the turbomachine component in arange between about 800° F. (426.6° C.) to about 900° F. (482.2° C.).14. The method of claim 12, wherein damping the vibration at the secondlevel occurs when the turbomachine component in a range between about900° F. (482.2° C.) to about 1400° F. (760° C.).
 15. The method of claim10, wherein mounting the damping structure to the surface of theturbomachine component comprises mounting the damping structure to aturbomachine bucket.
 16. The method of claim 10, wherein mounting thedamping structure to a surface of the turbomachine component comprisesmounting a material including stainless steel to the surface of theturbomachine component.